Lubricating compositions



United States Patent 3,359,202 LUBRICATING COMPOSITIONS Robert L. Stambaugh, Philadelphia, Pa., assignor to Rohm & Haas Company, Philadelphia, Pa., a corporation of Delaware N0 Drawing. Filed Oct. 29, 1965, Ser. No. 505,740 6 Claims. (Cl. 25233.4)

ABSTRACT OF THE DISCLOSURE This invention relates to oil compositions comprising a major portion of a mineral or synthetic oil and minor proportions of both an oil-soluble petroleum sulfonate and an alkylformamide. Use of both additives imparts a synergistic effect in the oil composition for inhibiting corrosion. The oil-soluble petroleum sulfonate may be in the form of its alkaline earth, calcium, magnesium or barium salt. The alkylformamides employed are those having the structure wherein the symbol A represents alkyl, the three alkyl groups having a total carbon content of 3 to 23 carbon atoms.

This invention deals with compositions comprising a major portion of a mineral or synthetic oil and minor proportions of an oil-soluble petroleum sulfonate and a structurally restricted alkylformamide.

It has already been proposed to add petroleum sulfonates to mineral oils to impart to the resulting compositions anti-corrosive properties or detergent action. Actual, practical results have varied greatly. In many instances, the protective value of the compositions has been insufficient at moderate concentrations of petroleum sulfonate. While larger proportions of such sulfonate have then been tried, the resulting compositions have not been proportionately more effective and disadvantageous properties have been thus developed. While compositions have been devised which give sufficient protection for slight or moderate exposure to corrosive conditions, these often fail when conditions become even somewhat more severe. This is particularly true in thin film applications. Often it is desirable or even necessary that the composition not only protect metals from corrosion but also provide safe and efficient lubrication. The present compositions possess this desirable combination of useful properties.

It is an object of this invention to provide compositions of improved anti-corrosive action, which supply a high degree of protection to metal surfaces, particularly ferrous surfaces, against corrosion from moisture and aqueous solutions of electrolytes. Surprisingly, the compositions of this invention have outstanding rust inhibition. This is particularly so when one considers the individual properties of the component parts.

One may use as an oil base any mineral or synthetic lubricant oil, including the petroleum stocks or the sebacates, azelates or other synthetic bases. An essential component of the compositions of this invention is an oilsoluble petroleum sulfonate. This is an alkaline earth salt, calcium, magnesium or barium, of the hydrocarbon sulfonates typically prepared by the treatment of petroleum oils with sulfuric acid followed, for example, by treatment with a base of the metal. These sulfonates may also be prepared by other synthetic techniques. Both are contemplated within the gamut of this invention. The most effective sulfonates are those of moderately high molec- 3,359,202 Patented Dec. 19, 1967 ular weight. These are usually regarded as having molecular weights of about 700 to about 1400. Yet any of the oil-soluble petroleum sulfonates may be used which have molecular weights from about 600 to about 2000, the range of 700 to 1400 being preferred, the only requirement being that the petroleum sulfonate be soluble in the particular mineral or synthetic oil selected at least to the extent of 0.2 to 7.5% by Weight. The oil-soluble alkaline earth petroleum sulfonates are used in amounts of about 0.2 to 7.5% by weight of the mineral or synthetic oil in which they are used, preferably one uses 0.5 to 5% by weight. While in any particular composition it is commercially advantageous to employ a single sulfonate, mixtures of these sulfonates may be employed, if desired, and such is contemplated within the bounds of this invention.

Typically, there may be employed the petroleum sulfonates of calcium, magnesium or barium of molecular weights of 400 to about 1000. These sulfonates may be of the neutral, substantially neutral or overbased types, as will be understood by those skilled in the art.

The alkylformamides employed are those having the structure wherein the symbol A represents alkyl, the three alkyl groups having a total carbon content of from 3 to 23 carbon atoms, preferably 7 to 23 carbon atoms. While single compounds will generally be employed, it is quite satisfactory to use mixtures within any one composition. In fact, commercially available mixtures of compounds wherein the A groups total from 11 to 14 and 17 to 23 carbon atoms are quite useful. Typically there may be employed N-t-butylformamide, N-t-octylformamide, N- t-dodecylformamide, N-t-tetradecylformamide, N-t-octadecylformamide, N t eicosylformamide, N-t-tetracosylformamide, alkyl-(C -C )formamide and alkyl-(C C )formamide.

These formamide are employed in the compositions in the range of 0.05 to 3.0% by weight of the oil in which they are used. The preferred range is 0.1 to 2.5 of the N- t-alkylformamide.

By rigid adherence to the definitions and proportions delineated above, one consistently observes outstanding rust inhibition, as evaluated in standard tests. One test that is employed to evaluate the present compositions is referred to as the Serive MS Sequence IIA Test, which is the API Service MS Sequence II Test, as described in ASTM Special Technical Publication 315, modified to use a 394 cubic inch displacement 1964 Oldsmobile V-8 engine. The test is run for 22 hours after which the engine is disassembled and rated for rust using CRC rating methods wherein 10 indicates free of rust. A corresponding bench test of use in evaluating the present compositions is based on the apparatus described in Technical Bulletin 63-36 of the National Petroleum Refiners Association. This apparatus is used in a test which includes the addition of 1.0 ml. of 2.0 N hydrochloric acid to ml. of test oil in a bottle containing a freshly sandblasted steel piece. The test is conducted for 20 hours at 176 F. At the conclusion of the test, the steel specimen is rated for rust, as noted above, wherein 10 equals free of rust.

The present invention may be more fully understood from the following illustrative examples. Parts by weight are used throughout.

Example 1 There are added 0.5 part of an N-t-alkylformamide (alkyl of C C and 1.0 part of an overbased calcium 3 sulfonate (molecular weight 940, total base number 300, 11.5% calcium) to 89.4 parts of a 170 SUS Mid-Continent Solvent Extracted Neutral Oil. The oil also contains standard amounts of a commercial VI improver, dispersant and oxidation and wear inhibitor. This formulation gives a rating of 9.2 in the above-described Sequence IIA Test.

Example 2 There are added 0.5 part of an N-t-butylformamide and 1.0 part of an overbased calcium sulfonate (molecular Weight 940, total base number 300, 11.5% calcium) to 89.7 parts of a 170 SUS Mid-Continent Solvent Extracted Neutral Oil. The oil also contains standard amounts of a commercial VI improver, dispersant and oxidation and wear inhibitor. This formulation gives a rating of 8.7 in the above-described bench test. A similar blend, without the N-t-butylformamide, gives a rating of 3.9. A similar blend, without the N-t-butylformamide and the overbased calcium sulfonate, gives a rating of 0.0.

Example 3 There are added 0.5 part of an N-t-alkylformamide (alkyl of C -C and 1.0 part of an overbased calcium sulfonate (molecular weight 940, total base number 300, 11.5% calcium) to 89.3 parts of a 170 SUS Mid-Continent Solvent Extracted Neutral Oil. The oil also contains standard amounts of a commercial VI improver, dispersant and oxidation and wear inhibitor. This formulation gives a rating of 9.9 in the aforementioned bench test. Without the N-t-alkylformamide, the rating is 3.9. Without the N-t-alkylformamide and overbased calcium sulfonate, the rating is 0.0.

Example 4 There are added 0.25 part of an N-t-alkylformamide (alkyl of C C and 1.0 part of an overbased magnesium sulfonate (molecular weight 920, total base number 300, 7.2% magnesium) to 89.6 parts of a 170 SUS Mid-Continent Solvent Extracted Neutral Oil. The oil also contains standard amounts of a commercial VI improver, dispersant and inhibitor for oxidation and wear. This formulation gives a rating of 8.8 in the aforementioned bench test. A similar blend, without the N-t-alkylformamide, gives a rating of 3.5. A similar blend, without the N-t-alkylformamide and the overbased magnesium sulfonate, gives a rating of 0.0.

Similar results are obtained using a synthetic sebacate oil base.

Example 5 There are added 1.5 parts of an N-t-alkylformamide (alkyl of C C and 4.3 parts of a neutral barium sulfonate (molecular weight 1030, total base number 8, 4.7% barium) to 85.3 parts of a 170 SUS Mid-Continent Solvent Extracted Neutral Oil. The oil also contains standard amounts of a commercial VI improver, dispersant and oxidation and wear inhibitor. This formulation gives satisfactory results in the bench test.

Similar results are obtained using a synthetic azelate oil base.

Example 6 There are added 0.5 part of an N-t-alkylformamide (alkyl of C C and 1.0 part of an overbased barium sulfonate (molecular weight 1030, total base number 60, 14.6% barium) to 89.3 parts of a SUS Mid-Continent Solvent Extracted Neutral Oil. The oil also contains standard amounts of a commercial VI improver, dispersant and oxidation and wear inhibitor. This formulation gives a bench test rating indicating three times more protection than is obtained by the sulfonate alone.

Example 7 There are added 2.5 parts of an N-t-alkylformamide (alkyl of C C and 5.0 parts of a neutral calcium sulfonate (molecular weight 892, total base number 0, 3.0% calcium) to 83.3 parts of a 170 SUS Mid-Continent Solvent Extracted Neutral Oil. The oil also contains standard amounts of a commercial VI improver, dispersant and oxidation and wear inhibitor. This formulation is twice as effective in the bench test as the corresponding blend without the formamide.

What is claimed is:

1. A lubricating composition comprising a major portion of an oil base and a minor portion sufficient to in hibit corrosion of an oil-soluble petroleum sulfonate in the form of its alkaline earth salt in the amount of about 012 to 7.5% by weight of said oil and an alkylformamide, in the amount of about 0.05 to 3% by weight of said oil, having the formula wherein A represents alkyl, the three alkyl groups having a total carbon content of 3 to 23 carbon atoms.

2. A composition according to claim 1 wherein said sulfonate is present in the amount of about 0.5 to 5% by weight of said oil and said alkylformamide is present in the range of about 0.1 to 2.5% by weight of said oil.

3. A composition according to claim 1 wherein said sulfonate is an overbased sulfonate of calcium, magnesium or barium.

4. A composition according to claim 1 wherein the alkyl portion of said alkylformamide contains 8 to 24 carbon atoms.

5. A composition according to claim 1 wherein said sulfonate is an overbased calcium sulfonate and said alkylformamide contains 12 to 15 carbon atoms in the alkyl portion.

6. A composition according to claim 1 wherein said sulfonate is an overbased calcium sulfonate and said alkylformamide contains 18 to 24 carbon atoms in the alkyl portion.

References Cited UNITED STATES PATENTS 2,501,731 3/1950 Mertes 252-33.4 X 2,916,451 12/1959 Faust 25233.4 2,956,020 10/1960 Suprin et al. 25233.4

OTHER REFERENCES T-alkylformamides Bulletin SP-315, Special Products Bulletin of Rohm and Haas Co. Six pages. November, 1964.

DANIEL E. WYMAN, Primary Examiner.

P. P. GARVIN, Examiner, 

1. A LUBRICATING COMPOSITION COMPRISING A MAJOR PORTION OF AN OIL BASE AND A MINOR PORTION SUFFICIENT TO INHIBIT CORROSION OF AN OIL-SOLUBLE PETROLEUM SULFONATE IN THE FORM OF ITS ALKALINE EARTH SALT IN THE AMOUNT OF ABOUT 0.2 TO 7.5% BY WEIGHT OF SAID OIL AND AN ALKYLFORMAMIDE, IN THE AMOUNT OF ABOUT 0.05 TO 3% BY WEIGHT OF SAID OIL, HAVING THE FORMULA 